I just got done building my 383 stroker motor and the other week when I took it up around 6200rpms and the crankshaft broke?????? I had a tech balance the motor or so he said... he told me that he balanced it out to 8000rpms and when I took it up alittle over 6000rpms it breaks????? It was a cast crankshaft but he said it would be fine.... now I'm getting a forged crank and a liquid damper but I am wondering if it's even worth my money to have it balanced out again??? Any advice would be greatly appreicated.

 

balancing is always worth it,i do think it is strange that the crank broke!
who was the manufactuer? i will guess--------hmmm------hmmm EAGLE:

 

Everything will need to be rebalanced. Well not really. If the pistons and rods are still ok, as long as they stay matched up, they should all be balanced the same. The crank will need to be balanced to match the rods and piston weights so everything needs to be sent out for rebalancing again.

Whenever using used parts such as a cast crank, part of the machine work is spending the extra cash and getting it magnafluxed. If it has a crack, it can break at any time. An uncracked cast crank can take more abuse than most people will believe.

Whenever you use any non factory parts or mismatched factory parts, the rotating assembly needs to be balanced.

 

yeah it was an eagle crank.....I have the sheets to the balance job the guy did. I don't know if I should take it back to him or go somewhere else? and If I have to pull the pistions and everything back out then should I drop my compression ratio down with some domed pistions?.....so I can hit the motor with some boost? because I don't know if I should go that route or just save my money for a new motor like a ls1 and build it up?

 

before you go speding a ton of cash,get the motor apart to see what all got hurt.you may not be in it too bad $ wise........
flip side the internals are damaged enough to warrant new rods/pistons or possibly block repairs i would part it out then but an Ls1 or a 6.0
$ 4 $ the 6.0 is a better choice.
good luck bro

 

yeah I know I wish I would have went that route instead but seeing as I don't have $9000 to spend on a GTO ls2 motor its out of the ?........however the ls1's seem to be a good price but I dont know how long it would take me to get it in my car and I kinda need a car ASAP.

 

yeah i know $$$$$$
look at salvage yards for escalades,denali's they have 6.0's usually 1500-4500

 

yeah but then I think I also need the new K-member and A-arms. along with a custom driveshaft right? how much would those be???? If I could get some of my money back out of the parts I have and get a ls1 swap and just throw a cam in it before dropping it in then I would do it.....but how long would it take?? oh and I'm not much of a wiring guy so how would I rewire everything?

 

Was the crankshaft used? Did you drop the crankshaft? Post pictures of this crankshaft, I have seen many fractures on fatigue test probes (I work in some crankshaft developement), I would like to see if the failure mode is the same.

 

Where did it break? that's a MAJOR clue to the cause.

What crank damper did it have on it?

What was it doing when it broke?

If you have the balance specs that the crank was set up to (bob weights0 it is possible to replicate the balance without disassembling the rest of the motor. IF AND ONLY IF of course, it was shut down as soo as it happened, and not allowed to run until it just wouldn't run any more, and filled up the oil passages with metal shavings; in which case any crank you put in, will IMMEDIATELY have its bearing journals destroyed by the chips.